The present invention relates to an optically guided, unmanned or driverless load transporting vehicle. More particularly, the invention relates to such a load transporting vehicle which employs a camera tube such as an industrial television camera, can be automatically controlled, that is, automatically steered, run and stopped, and which can be readily introduced into even an existing factory, or the like, and which has a novel means for detecting a guide belt.
Conventionally, in order to run an unmanned lifting truck such as a fork-lift truck having prongs which can be raised or lowered, often a guide line, which radiates a guiding signal, has been buried in the floor of the facility where it is to be used. A pair of pickup coils is then installed on the body of the truck such that the guide line is interposed between the pickup coils. A voltage difference induced between the coils is detected to control the truck. Usually, such a guide line is either received in a groove formed in the floor or buried in the floor. Installation in the former arrangement is difficult, while the latter requires a large number of steps, including forming a groove in the floor of an already-constructed building. Further, in the case of a relatively thin concrete floor as may be encountered above the ground level, it is difficult to form such a groove. Another problem is that steel bars embedded in the concrete work may emit a secondary electromagnetic radiation which disturbs the control signal. Also, if the line is broken, the whole running course may be made useless. Further, in a nuclear power plant, due to the possibility of radioactive waste accumulating in a groove, a grooved track may not be possible.
Further, radio control of vehicles is known, but such systems are readily affected by noise.
It is also known to embed a magnet or similar means in the floor at junctions or the like. This technique is, however, accompanied by difficulties similar to those encountered in case of the induction lines buried in a recess in the floor.
Optical guide systems are also known in which geometrical patterns, such as triangles and circles, are provided on the floor to control unmanned trucks. Unfortunately, it takes a computer a long time to recognize the patterns. Further, the number of such patterns is limited, thus providing only a limited quantity of information which may be used for control, resulting in poor responsiveness in the system.
In view of the foregoing difficulties, it is a main object of the present invention to provide an unmanned load transporting vehicle which dispenses with the formation of grooves or recesses in floor.
It is another object of the invention to provide an unmanned load transporting vehicle which can be run with higher certainty and accuracy than is possible with conventional approaches.